Proton MR spectroscopy for the evaluation of brain injury in asphyxiated, term neonates

Neurologic and developmental outcomes of asphyxiated, term neonates are difficult to predict applying clinical or laboratory criteria. In this study, we investigated the association of MR spectroscopy (MRS) results with neurodevelopmental status at age 12 months.

Thirty-one term neonates, who were enrolled in a prospective study of the utility of MR imaging for the determination of neurologic and developmental status, underwent single-voxel proton MRS of the basal nuclei and intervascular boundary zones. Ratios of lactate, choline, creatine, and N-acetylaspartate (NAA) peaks were calculated and tested for association with neuromotor scores and Mental Development Index of the Bayley Scores of Infant Development obtained at age 12 months.

Elevated lactate and diminished NAA were the most common findings in infants with neurologic and developmental abnormalities at age 12 months. Although many ratios had statistically significant associations with outcome (P<.05), the highest significance was obtained with lactate/choline ratios in the basal nuclei. A false-positive finding was seen in a patient who was born after a 36-week gestation period (high lactate/choline but normal neurodevelopmental status at 12 months) and in three patients with apparent watershed injury (high watershed lactate/choline but normal neurodevelopmental status at 12 months). A false-negative MRS finding (normal lactate/choline but abnormal outcome) was seen in a patient who had an apparent prenatal injury.

Proton MRS appears to be a useful tool for assessing brain injury in neonates who have suffered hypoxia or ischemia. Correlation with gestational age and imaging findings are essential for proper interpretation of the spectra. Patients with apparent watershed injuries may have normal neurodevelopmental status at age 12 months.